Abstract：
CONCLUSIONS: Key message Three major QTLs for resistance to downy mildew were located within an 0.78 Mb interval on chromosome 8 in foxtail millet. Downy mildew, a disease caused by Sclerospora graminicola, is a serious problem that jeopardizes the yield and quality of foxtail millet. Breeding resistant varieties represents one of the most economical and effective solutions, yet there is a lack of molecular markers related to the resistance. Here, a mapping population comprising of 158 F6:7 recombinant inbred lines (RILs) was constructed from the crossing of G1 and JG21. Based on the specific locus amplified fragment sequencing results, a high-density linkage map of foxtail millet with 1031 bin markers, spanning 1041.66 cM was constructed. Based on the high-density linkage map and the phenotype data in four environments, a total of nine quantitative trait loci (QTL) associated with resistance to downy mildew were identified. Further BSR-seq confirmed the genomic regions containing the potential candidate genes related to downy mildew resistance. Interestingly, a 0.78-Mb interval between C8M257 and C8M268 on chromosome 8 was highlighted because of its presence in three major QTL, qDM8_1, qDM8_2, and qDM8_4, which contains 10 NBS-LRR genes. Haplotype analysis in RILs and natural population suggest that 9 SNP loci on Seita8G.199800, Seita8G.195900, Seita8G.198300, and Seita.8G199300 genes were significantly correlated with disease resistance. Furthermore, we found that those genes were taxon-specific by collinearity analysis of pearl millet and foxtail millet genomes. The identification of these new resistance QTL and the prediction of resistance genes against downy mildew will be useful in breeding for resistant varieties and the study of genetic mechanisms of downy mildew disease resistance in foxtail millet.
摘要：
结论：关键信息谷子抗霜霉病的三个主要QTL位于8号染色体0.78Mb间隔内。霜霉病,一种由scraminicola引起的疾病，是危害谷子产量和品质的严重问题。选育抗病品种代表了最经济和有效的解决方案之一，然而，缺乏与抗性相关的分子标记。这里,从G1和JG21的杂交构建包含158个F6:7重组自交系(RIL)的作图群体。根据特定基因座扩增片段测序结果，具有1031个bin标记的谷子高密度连锁图，跨度为1041.66cM。基于高密度连锁图谱和四种环境下的表型数据，总共鉴定了9个与霜霉病抗性相关的数量性状位点（QTL）。进一步的BSR-seq证实了包含与霜霉病抗性相关的潜在候选基因的基因组区域。有趣的是,8号染色体上C8M257和C8M268之间的0.78-Mb间隔突出显示，因为它存在于三个主要的QTL中，qDM8_1，qDM8_2和qDM8_4，其中包含10个NBS-LRR基因。RIL和自然种群的单倍型分析表明，Seita8G.199800，Seita8G.195900，Seita8G.198300和Seita8G199300基因上的9个SNP位点与抗病性显着相关。此外，通过对小米和谷子基因组的共线性分析，我们发现这些基因具有分类单元特异性。这些新的抗病QTL的鉴定和抗霜霉病基因的预测将有助于谷子抗病品种的选育和抗霜霉病遗传机制的研究。
